The only dolphin in the Baltic Sea seems to like muttering to himself. Researchers are trying to figure out why.

Marine biologists are perplexed by the lone bottlenose dolphin's vocalizations, because some resemble sounds typically used for communication

When you are alone, especially for long periods of time, do you talk to yourself? If so, you’re in interesting company because a male Atlantic bottlenose dolphin who has been living alone in the Baltic Sea for more than three years, appears to be talking to himself.

What happens when a highly social creature like a bottlenose dolphin is left utterly alone? Delle, a solitary dolphin in Denmark, may be showing us.

The researchers listened in on Delle with an underwater microphone for 69 days, between December 8, 2022, and February 14, 2023. Though they initially weren’t expecting much, the researchers say they detected communicative sounds in 35 out of the 69 days.